Fabrics woven with warps and wefts have conventionally been used widely as an industrial fabric. They are used in various fields including papermaking wires, conveyor belts and filter cloths and required to have fabric properties suited for the intended use or using environment. Of such fabrics, a papermaking wire used in a papermaking step for removing water from raw materials by making use of the meshes of a fabric must satisfy severe requirements. There is therefore a demand for the development of fabrics which have an excellent surface property and therefore do not transfer a wire mark of the fabric to paper, have enough wear resistance and rigidity and are therefore usable desirably even under severe environments, and are capable of maintaining conditions necessary for making good-quality paper for a long period of time. In addition, fiber supporting property, improvement in a papermaking yield, good water drainage property, dimensional stability and running stability are required. In recent years, owing to the speed-up of a papermaking machine, requirements for papermaking wires become severe further.
Since most of the requirements for the industrial fabric and how to satisfy them can be understood by describing a papermaking fabric on which the most strict requirement is imposed among industrial fabrics, the present invention will hereinafter be described using the papermaking fabric as a representative example.
It is very important for papermaking fabrics to have, in particular, excellent surface property which does not facilitate transfer of a wire mark of a fabric to paper, fiber supporting property of holding fine fibers, wear resistance permitting long-term running even under strict running conditions, running stability permitting stable running until the final using stage and rigidity. Researches on the design or constitution of a fabric capable of satisfying these properties have been carried out. Two-layer fabrics having, as a portion of an upper side warp and a lower side warp stacked vertically, a warp binding yarn have recently been used as such a fabric. The warp binding yarn has a function of weaving and binding an upper side weft and a lower side weft, and at the same time has, similar to an upper side warp and a lower side warp, a function of forming a portion of an upper side surface and a lower side surface.
A two-layer fabric using a warp binding yarn is disclosed in Japanese Patent Laid-Open No. 2003-342889. This fabric uses a warp binding yarn. Without an additional binding yarn which may break an upper side fabric design, it has an excellent surface property. It is superior in binding strength to a fabric bound via a weft. The fabric described in this document, however, adopts a design in which a lower side weft constituting the lower side surface passes over two warps and then passes under two warps to form a short weft crimp corresponding to two lower side warps on the lower side surface. This fabric has a water drainage space between two adjacent pairs of lower side warps and is made of yarns with a small diameter so that it is suited as a fabric for the manufacture of tissue paper having a thin wire thickness. This fabric is suited as a fabric for manufacturing tissue paper, but is not suited for applications requiring wear resistance and rigidity. A lower side weft having a long crimp design is able to have improved wear resistance, but in a fabric using a warp binding yarn, the fabric design is sometimes limited by the diameter of a yarn, or structure or application of the resulting fabric. For example, even if a large-diameter yarn is used as the lower side weft of this fabric in order to increase its wear resistance, the lower side weft becomes unpliable and a warp appearing from the lower side tends to protrude and be worn away.
As described above, no industrial fabric using a warp binding yarn so far developed can simultaneously satisfy wear resistance, surface property, rigidity, running stability and water drainage property.